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Schramm WC, Bala N, Arekar T, Malik Z, Chacko KM, Lewis RL, Denslow ND, Scindia Y, Alli AA. Enrichment of Bioactive Lipids in Urinary Extracellular Vesicles and Evidence of Apoptosis in Kidneys of Hypertensive Diabetic Cathepsin B Knockout Mice after Streptozotocin Treatment. Biomedicines 2024; 12:1038. [PMID: 38791000 PMCID: PMC11117475 DOI: 10.3390/biomedicines12051038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/15/2024] [Accepted: 04/18/2024] [Indexed: 05/26/2024] Open
Abstract
Cathepsin B (CtsB) is a ubiquitously expressed cysteine protease that plays important roles in health and disease. Urinary extracellular vesicles (uEVs) are released from cells associated with urinary organs. The antibiotic streptozotocin (STZ) is known to induce pancreatic islet beta cell destruction, diabetic nephropathy, and hypertension. We hypothesized that streptozotocin-induced diabetic kidney disease and hypertension result in the release of bioactive lipids from kidney cells that induce oxidative stress and renal cell death. Lipidomics was performed on uEVs isolated from CtsB knockout mice treated with or without STZ, and their kidneys were used to investigate changes in proteins associated with cell death. Lysophosphatidylethanolamine (LPE) (18:1), lysophosphatidylserine (LPS) (22:6), and lysophosphatidylglycerol (LPG) (22:5) were among the bioactive lipids enriched in uEVs from CtsB knockout mice treated with STZ compared to untreated CtsB mice (n = 3 uEV preparations per group). Anti-oxidant programming was activated in the kidneys of the CtsB knockout mice treated with STZ, as indicated by increased expression of glutathione peroxidase 4 (GPX4) and the cystine/glutamate antiporter SLC7A11 (XCT) (n = 4 mice per group), which was supported by a higher reactivity to 4-hydroxy-2-nonenal (4-HNE), a marker for oxidative stress (n = 3 mice per group). Apoptosis but not ferroptosis was the ongoing form of cell death in these kidneys as cleaved caspase-3 levels were significantly elevated in the STZ-treated CtsB knockout mice (n = 4 mice per group). There were no appreciable differences in the pro-ferroptosis enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4) or the inflammatory marker CD93 in the kidneys (n = 3 mice per group), which further supports apoptosis as the prevalent mechanism of pathology. These data suggest that STZ treatment leads to oxidative stress, inducing apoptotic injury in the kidneys during the development of diabetic kidney disease and hypertension.
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Affiliation(s)
- Whitney C. Schramm
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Niharika Bala
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Tanmay Arekar
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
| | - Zeeshan Malik
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Kevin M. Chacko
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Russell L. Lewis
- Department of Physiological Sciences, Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32608, USA; (R.L.L.); (N.D.D.)
| | - Nancy D. Denslow
- Department of Physiological Sciences, Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL 32608, USA; (R.L.L.); (N.D.D.)
| | - Yogesh Scindia
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32608, USA
| | - Abdel A. Alli
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL 32610, USA; (W.C.S.); (N.B.); (T.A.); (Z.M.); (K.M.C.); (Y.S.)
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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Aufy M, Hussein AM, Stojanovic T, Studenik CR, Kotob MH. Proteolytic Activation of the Epithelial Sodium Channel (ENaC): Its Mechanisms and Implications. Int J Mol Sci 2023; 24:17563. [PMID: 38139392 PMCID: PMC10743461 DOI: 10.3390/ijms242417563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/10/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023] Open
Abstract
Epithelial sodium channel (ENaC) are integral to maintaining salt and water homeostasis in various biological tissues, including the kidney, lung, and colon. They enable the selective reabsorption of sodium ions, which is a process critical for controlling blood pressure, electrolyte balance, and overall fluid volume. ENaC activity is finely controlled through proteolytic activation, a process wherein specific enzymes, or proteases, cleave ENaC subunits, resulting in channel activation and increased sodium reabsorption. This regulatory mechanism plays a pivotal role in adapting sodium transport to different physiological conditions. In this review article, we provide an in-depth exploration of the role of proteolytic activation in regulating ENaC activity. We elucidate the involvement of various proteases, including furin-like convertases, cysteine, and serine proteases, and detail the precise cleavage sites and regulatory mechanisms underlying ENaC activation by these proteases. We also discuss the physiological implications of proteolytic ENaC activation, focusing on its involvement in blood pressure regulation, pulmonary function, and intestinal sodium absorption. Understanding the mechanisms and consequences of ENaC proteolytic activation provides valuable insights into the pathophysiology of various diseases, including hypertension, pulmonary disorders, and various gastrointestinal conditions. Moreover, we discuss the potential therapeutic avenues that emerge from understanding these mechanisms, offering new possibilities for managing diseases associated with ENaC dysfunction. In summary, this review provides a comprehensive discussion of the intricate interplay between proteases and ENaC, emphasizing the significance of proteolytic activation in maintaining sodium and fluid balance in both health and disease.
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Affiliation(s)
- Mohammed Aufy
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
| | - Ahmed M. Hussein
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
- Department of Zoology, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt
| | - Tamara Stojanovic
- Programme for Proteomics, Paracelsus Medical University, 5020 Salzburg, Austria;
| | - Christian R. Studenik
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
| | - Mohamed H. Kotob
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
- Department of Pathology, Faculty of Veterinary Medicine, Assiut University, Assiut 71515, Egypt
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Dogan YE, Bala N, Chacko KM, Tuna KM, Alli AA. Tempol treatment normalizes membrane expression of epithelial transport proteins in the kidney of salt-loaded hypertensive diabetic db/db mice. Am J Transl Res 2023; 15:6690-6700. [PMID: 38186979 PMCID: PMC10767517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/14/2023] [Indexed: 01/09/2024]
Abstract
OBJECTIVE Hypertension exacerbates the progression and severity of diabetic kidney disease. In this study, we addressed the hypothesis that tempol acts at multiple segments of the nephron to normalize the abundance of sodium coupled epithelial transport proteins in the luminal plasma membrane to mitigate high blood pressure in salt-loaded hypertensive diabetic db/db mice. METHODS Soluble and membrane fractions from freshly homogenized kidney cortex tissue samples were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and probed for specific proteins by Western blotting. Western blotting for specific urinary extracellular vesicle (uEV) markers and nanoparticle tracking analysis was performed to characterize each uEV preparation from each group. A one-way ANOVA was performed to determine statistical significance between three groups (hypertensive diabetic db/db mice treated with vehicle, hypertensive diabetic db/db mice treated with tempol, and wild-type mice). RESULTS Tempol treatment reduced systolic blood pressure in hypertensive diabetic db/db mice compared to db/db mice that received vehicle. We observed attenuated membrane protein expression of the sodium hydrogen exchanger 3 (NHE3), sodium potassium chloride co-transporter (NKCC2), sodium chloride cotransporter (NCC), and epithelial sodium channel (ENaC) in the kidney of salt-loaded hypertensive diabetic db/db mice infused with tempol by osmotic minipump for 5 days compared to hypertensive diabetic db/db mice infused with vehicle. Also, the infusion of tempol in hypertensive diabetic db/db mice reduced the augmented protein expression of protein kinase c (PKC) epsilon observed in the vehicle treated hypertensive diabetic db/db kidney when compared to the healthy wild-type kidney. The amount of uEV and their size profiles were comparable between the three groups. CONCLUSIONS This study demonstrates that tempol down-regulates epithelial transport mechanisms in each segment of the nephron and normalizes salt-induced high blood pressure in diabetic animals presumably in a PKC dependent manner.
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Affiliation(s)
- Yunus E Dogan
- Department of Physiology and Aging, College of Medicine, University of FloridaGainesville Florida 32610, USA
- Department of Pediatrics, Faculty of Medicine, Erciyes UniversityKayseri, Turkey
| | - Niharika Bala
- Department of Physiology and Aging, College of Medicine, University of FloridaGainesville Florida 32610, USA
| | - Kevin M Chacko
- Department of Physiology and Aging, College of Medicine, University of FloridaGainesville Florida 32610, USA
| | - Kubra M Tuna
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, College of Medicine, University of FloridaGainesville Florida 32610, USA
| | - Abdel A Alli
- Department of Physiology and Aging, College of Medicine, University of FloridaGainesville Florida 32610, USA
- Department of Medicine, Division of Nephrology, Hypertension and Renal Transplantation, College of Medicine, University of FloridaGainesville Florida 32610, USA
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Alli AA. Extracellular Vesicles: Investigating the Pathophysiology of Diabetes-Associated Hypertension and Diabetic Nephropathy. BIOLOGY 2023; 12:1138. [PMID: 37627022 PMCID: PMC10452642 DOI: 10.3390/biology12081138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/03/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023]
Abstract
Extracellular vesicles (EVs) include exosomes, microvesicles, and apoptotic bodies. EVs are released by all cell types and are found in biological fluids including plasma and urine. Urinary extracellular vesicles (uEVs) are a mixed population of EVs that comprise small EVs that are filtered and excreted, EVs secreted by tubular epithelial cells, and EVs released from the bladder, urethra, and prostate. The packaged cargo within uEVs includes bioactive molecules such as metabolites, lipids, proteins, mRNAs, and miRNAs. These molecules are involved in intercellular communication, elicit changes in intracellular signaling pathways, and play a role in the pathogenesis of various diseases including diabetes-associated hypertension and diabetic nephropathy. uEVs represent a rich source of biomarkers, prognosis markers, and can be loaded with small-molecule drugs as a vehicle for delivery.
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Affiliation(s)
- Abdel A. Alli
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, FL 32610, USA; ; Tel.: +1-352-273-7877
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, FL 32610, USA
- Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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Gholam MF, Bala N, Dogan YE, Alli AA. Augmentation of Cathepsin Isoforms in Diabetic db/db Mouse Kidneys Is Associated with an Increase in Renal MARCKS Expression and Proteolysis. Int J Mol Sci 2023; 24:12484. [PMID: 37569859 PMCID: PMC10419664 DOI: 10.3390/ijms241512484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/29/2023] [Accepted: 07/31/2023] [Indexed: 08/13/2023] Open
Abstract
The expression of the myristoylated alanine-rich C-kinase substrate (MARCKS) family of proteins in the kidneys plays an important role in the regulation of the renal epithelial sodium channel (ENaC) and hence overall blood pressure regulation. The function of MARCKS is regulated by post-translational modifications including myristoylation, phosphorylation, and proteolysis. Proteases known to cleave both ENaC and MARCKS have been shown to contribute to the development of high blood pressure, or hypertension. Here, we investigated protein expression and proteolysis of MARCKS, protein expression of multiple protein kinase C (PKC) isoforms, and protein expression and activity of several different proteases in the kidneys of diabetic db/db mice compared to wild-type littermate mice. In addition, MARCKS protein expression was assessed in cultured mouse cortical collecting duct (mpkCCD) cells treated with normal glucose and high glucose concentrations. Western blot and densitometric analysis showed less abundance of the unprocessed form of MARCKS and increased expression of a proteolytically cleaved form of MARCKS in the kidneys of diabetic db/db mice compared to wild-type mice. The protein expression levels of PKC delta and PKC epsilon were increased, while cathepsin B, cathepsin S, and cathepsin D were augmented in diabetic db/db kidneys compared to those of wild-type mice. An increase in the cleaved form of MARCKS was observed in mpkCCD cells cultured in high glucose compared to normal glucose concentrations. Taken together, these results suggest that high glucose may contribute to an increase in the proteolysis of renal MARCKS, while the upregulation of the cathepsin proteolytic pathway positively correlates with increased proteolysis of MARCKS in diabetic kidneys, where PKC expression is augmented.
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Affiliation(s)
- Mohammed F. Gholam
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
- Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Jeddah 22384, Saudi Arabia
| | - Niharika Bala
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Yunus E. Dogan
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Abdel A. Alli
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
- Department of Medicine Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610, USA
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Kawakibi T, Bala N, Liu LP, Searcy LA, Denslow ND, Alli AA. Decreased MARCKS Protein Expression in Kidney Cortex Membrane Fractions of Cathepsin B Knockout Mice Is Associated with Reduced Lysophosphatidylcholine and Protein Kinase C Activity. Biomedicines 2023; 11:1489. [PMID: 37239160 PMCID: PMC10216610 DOI: 10.3390/biomedicines11051489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/28/2023] [Accepted: 05/12/2023] [Indexed: 05/28/2023] Open
Abstract
Cathpesin B is a multi-functional protease that plays numerous roles in physiology and pathophysiology. We hypothesized that actin cytoskeleton proteins that are substrates of cathepsin B, various lipids, and kinases that are regulated by lipids would be down-regulated in the kidney of cathepsin B knockout mice. Here, we show by Western blot and densitometric analysis that the expression and proteolysis of the actin cytoskeleton proteins myristoylated alanine-rich C-kinase substrate (MARCKS) and spectrin are significantly reduced in kidney cortex membrane fractions of cathepsin B knockout mice compared to C57B6 wild-type control mice. Lipidomic results show that specific lipids are increased while other lipids, including lysophosphatidylcholine (LPC) species LPC (16:0), LPC (18:0), LPC (18:1), and LPC (18:2), are significantly decreased in membrane fractions of the kidney cortex from Cathepsin B null mice. Protein Kinase C (PKC) activity is significantly lower in the kidney cortex of cathepsin B knockout mice compared to wild-type mice, while calcium/calmodulin-dependent protein kinase II (CaMKII) activity and phospholipase D (PLD) activity are comparable between the two groups. Together, these results provide the first evidence of altered actin cytoskeleton organization, membrane lipid composition, and PKC activity in the kidneys of mice lacking cathepsin B.
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Affiliation(s)
- Tamim Kawakibi
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Niharika Bala
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Lauren P. Liu
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Louis A. Searcy
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida College of Veterinary Medicine, Gainesville, FL 32610, USA
| | - Nancy D. Denslow
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida College of Veterinary Medicine, Gainesville, FL 32610, USA
| | - Abdel A. Alli
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610, USA
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